and children. In the case of drowned children who have fallen into water and immediately stopped breathing can be suffering from mamillian diving reflex which gives the appearance of death. CPR is still appropriate. Even if the child has fallen in a pond and has been in for some time, MDR can preserve the brain for extraordinary lengths of time, so don't give up till the paramedics have (and sometimes even after that) *ahem*CPR is to extend the period of time available until the professionals arrive Also, blood stream already has O2 in it. When you're pumping on the chest, the chest will exhale and inhale fresh air, but it won't go as deep into the airsacks. Always confirm help is on the way before starting, 30 compressions, 2 rescue breaths to be repeated ad nauseum until you collapse, help arrives or you give up. Most inexperienced people who have done a 1-4 day course in first aid forget to open the airway correctly, inflating the stomach and creating a juice box effect. (boo, there's no puking smilies) You can't shock someone who isn't in fibrillation. If they're in asystole (flatlining) then you're not doing anything by shocking them as a shock is meant to stop the heart not to start it. The idea is by stopping it, it'll stop fibrillating and will restart "normally" Yes, if CPR is done at the right depth breaking ribs is possible and likely. On the two times I've had to do CPR it's been pretty much spot on (the AEDs measure all sorts and record so they can gather data). Both guys had broken ribs by the time the four of us had had a go and the paramedics had arrived!